1. Field of the Invention
The present invention relates to image processing apparatuses, and more particularly, to an image processing apparatus suitable for computer systems such as a personal computer and a work station, domestic information terminals such as a HA (Home Automation) system and portable information terminals, and also communication systems of television telephones and television conferences.
2. Description of the Background Art
A conventional image processing apparatus compresses image data by converting a video signal from a video movie camera or the like into an intermediate format called a CIF (Common Intermediate Format). The compressed image data is transmitted via a telephone line.
Such an image processing apparatus will be described hereinafter with reference to FIG. 71 showing a structure of a conventional image processing apparatus.
Referring to FIG. 71, an image processing apparatus includes a video movie 201, an A/D converter 202, a luminance signal processing circuit 203, a color signal processing circuit 204, an image conversion circuit 205, and a frame memory 206.
An analog video signal or a YC separation signal from video movie 201 is converted into a digital video signal by A/D converter 202. Digital luminance signal Y and digital color signal C of the digital video signal are processed by luminance signal processing circuit 203 and color signal processing circuit 204, respectively, to be provided to image conversion circuit 205. The digital video signals processed by each of processing circuits 203 and 204 are stored in frame memory 206 via image conversion circuit 205. Image conversion circuit 205 reads out the digital video signal stored in frame memory 206 to convert the same into a CIF format by applying frame frequency conversion, line conversion, and pixel conversion thereto. Such a conventional image processing apparatus is disclosed in for example, Japanese Patent Laying-Open Nos. 4-229789 and 4-185087.
Because such a conventional image processing apparatus has to carry out complicated frame frequency conversion, pixel conversion, and line conversion, the circuit complexity thereof is increased. An additional complexity is that a frame memory is required. Furthermore, when an arbitrary image format conversion is to be carried out, the storage capacity required for the frame memory is increased, resulting in even greater circuit complexity. When compressed image data is to be generated by skipping image data, the converted image is reduced in size, and there is a possibility of distortion in the resulting image.